In recent years, interest in compostable polymers, i.e. biopolymers, has greatly increased, and many companies have made efforts to market, for example, packaging materials, hygiene products, sacks, and films with compostable polymers. Polylactic acid (PLA), i.e., polylactide, or condensation polymers which are based on lactic acid, are for many reasons a very attractive group of biopolymers. Their principal degradation product, lactic acid, is a product common in nature, it is not toxic and is used widely in the food and pharmaceutical industries.
Films, particularly blown films, comprising PLA have proven difficult to manufacture. Indeed, currently available PLA blown films require the addition of additives such as plasticizers to enable their production. However, plasticizers are often undesirable for films with food-related applications; they are costly; and they seldom, if at all, are as environmentally friendly as PLA itself. To circumvent these issues, some manufacturers have resorted to manufacturing PLA film with casting methodology (e.g., cast and tenner). However, casting methodology produces films with limited applications and can be 5 to 10 times more costly than blown film processing.
Accordingly, there is a need for PLA blown films substantially free of plasticizers. There is also a need for a method of manufacturing PLA films using blown film processing.